Piston



April 9, 1929. FREER 1,708,500

PISTON Filed Jan. 18, 1928 2 Sheets-Sheet 1 p l .9, 1929; P. M; FREER1,708,500

PISTON Filed Jan. 18, 1928 2 Sheets-Sheet 3 INVENTOR BY flee 1 '7 W AjTORNEY Patented Apr. 9, 1929.

UNITED STATES PATENT OFFICE.

I PHELPS M. FREEROF DETROIT, MICHIGAN, ASSIGNOR OF FORTY-NINE PER CENT TALEXANDER C. HAMILTON, OF DETROIT, MICHIGAN, AND FIFTY-ONE YER CENT T0CHARLES H. LEWIS, OF CLEVELAND, OHIO.

PISTON.

Application filed January 18, 1928. Serial No. 247,605.

The invention relates to improvements in pistons designed particularlyfor use in internal combustion engines, as described in the presentspecification and illustrated in the accompanying drawings that formpart of the same.

The objects of the invention are to provide a composite pistoncomprising a head of light material having high heat conductingqualities, and a skirt of maximum wearing qualities joined to the headby a simple form of spring bracelet.

In the drawings- Fig. 1 is an elevation View of the piston withsubstantially one-quarter broken away.

Fig. 2 is a plan view of the piston from the under side.

Fig. 3 is a side elevation detail view of the head with one-quarterthereof broken away.

Fig. 4 is a side elevation view of the spring bracelet.

Fig. 5 is a side elevation view of the sklrt.

Fig. 6 is a detail View of the aligning pin.

7 is a plan view of the spring bracelet.

Fig. 8 is a detail view of a modified form.

Fig. 9 is a partially broken side view of the piston showing amodification of the means for maintaining concentricity of the head andthe skirt.

Fig. 10 is a side elevation of the modified spring bracelet embodied inthe construction shown in Fig. 9.

Fig. 11 is a sectional View taken on line iii-11 of Fig. 9.

Fig. 12 is a partially broken side elevation of the skirt memberemployed in the construction shown in Fig. 9.

Fig. 13 is a fragmentary sectional view taken on the line 1313 of Fig.9. illustrating the manner in which the locking fingers engage theircooperating grooves.

Like numerals of reference indicate corresponding parts in each figure.

lower end, and extends downwardly from a locking shoulder 15.

The head as described is preferably made of cast aluminum or other lightalloy having maximum heat conducting qualities, while the skirt 16 ismade of a metal such as a. cast nickel iron alloy or the like, whichpossesses high wearing qualities and a very low coefiicient ofexpansion.

The skirt 16 is made of a plain cylindrical form having the small ledgeor inwardly extending flange 17 around the bot-tomfor reinforcingpurposes, and likewise the inwardly extending flange 18 around the top,the flange 18 being finished on its under side 19 with a bevel of adefinite angle for purposes as hereinafter described. The head and skirt16 are cast and finished as separate pieces, and are then joined by aspring bracelet 20 formed with the inturned lower end 21 and theupwardly and outwardly extending fingers 22 and 23, the fingers 22 beingslightly longer than the fingers 23, so that the bracelet may be sprungaround the lower part 12 of the head similar to a piston ring, with thelower int-urned end 21 fitting snugly in the groove 14 on the head.

To assemble the parts the skirt is pressed upwardly against the head,causing the fingers 22 and 23 of the bracelet 20 to spring inwardlyuntil the flange 18 passes the ends of the fingers and abuts the flange15 on the head, at which time the fingers are of such length that theywill just have cleared the flange 18 and will bear against the bevelledunder side 19 of said flange.

he fingers. being of unequal length, will press outwardly to differentextents. and will always assure taking up of play between the skirt andthe head at the pistonand yet will permit of the necessary movement between the head and the skirt due to unequal ex mansion between anormally cold temperature and a temperature that may be attained whenthe piston has been running even under excessive compression conditionsin the. engine cylinder. I

To maintain true concentricity between the head and the skirt at alltimes, lateral holes 2 1 are drilled at the juncture of the head and theskirt, and pins 25 are dri into the said holes and peencd therein insuitable manner. These pins are preferabl four in number, as shown inFig. 2, thougl i three may sufiice, and it will be noted that thediametrically opposite pins will prevent any corresponding lateralmovement of the head and skirt, and thus hold them concenwithin thecorresponding slots 36 which closelv embrace the sides of the same andthere ore act in the same manner asthe pins 24 previously described, tomaintain true concentricity between the head and the skirt.

As indicated in Fig. 13, the sides of the grooves 36 arepreferablytapered so that the fingers 35 in drop ing into the grooves 36 willengage the si es of the grooves before they can reach the bottomsthereof. This construction insures close fit of the fingers 35 with thesides of the grooves so as to prevent any possible lateral movement ofthe skirt portion 16- with respect to the collar- 20, and at the sametime provides a construction which allows greater manufacturingtolerances in the width of the fingers 35 and grooves 36 thanwouldotherwise be possible.

In order to prevent possible rotation of the head with respect to theskirt in this construction, inwardly extending projections 37 are formedat the inner edge of the bracelet 20, and matching depressions 38 areformed in the bottom of the groove 14 so that when the bracelet 20 is inoperative position it is locked against rotation to the head.

It will be readily understood that if it is desired to make the skirt ofa sheet metal, the upper part thereof may be turned downwardly to formspring fingers as shown in detail in Fig. 8, wherein the head is shownat 26 with the extending lower portion 27 formed with a beveled flange28 at its extreme lower end, and the skirt of drawn material is shown at29 with its upper end turned inward at 30 to abut the head, and thefingers 31 extending downward in such turned-in portion to springagainst the beveled flange 28.

Other modifications may be made in the construct-ions without departingfrom the spirit of the invention, which broadly covers the uniting ofthe head and skirt by means of the spring fingers of different lengths,which maintain a constant pressure of the head against the skirt, andyet permit the necessary differences in expansion, and the provision ofmeans for maintaining the concentricity of the head with respect to theskirt.

What I claim is:

- 1. A piston comprising a head, and a skirt sleeved over a portion ofthe head and having spring fingers of unequal length for connecting thetwo together.

2. A piston comprising a head, a skirt sleeved over a portion of thehead, and a ring-like member surrounding said head within said skirt forconnecting the two together, said ring-like member being provided withresilient fingers of alternately different lengths.

3. A piston comprising a head member and a skirt member secured togetherin sleeved relationship by a plurality of spring fingers of differentlengths.

4. A piston comprising a head member and a skirt member secured togetherin sleeved relationship by a plurality of spring fingers, and means formaintaining the concentricity of said members.

5. A piston comprising a head member and a skirt member secured togetherin sleeved relationship by a plurality of spring fingers, and means forpreventing rotational movement of one of said members relative to theother thereof.

6. A piston comprising a head member and a skirt member secured togetherin sleeved relationship by a coronal collar provided with s ringfingers, and means for maintaining t e concentricity of said memberscomprising a plurality of radially extending pins engaging both of saidmembers.

7. A piston comprising a head member and a skirt member secured togetherin sleeved relationship by spring fingers and means for maintainingooncentricity of said members comprising radial pins inserted in saidmembers at their juncture.

.8. A piston comprising a pair of members secured together in sleevedrelationship by means of a collar rovided with resilient fingers, andmeans or preventing rotation 10f one of said members relative to saidcol- 9. A piston comprising a head member and a skirt member securedtogether in sleeved relationship by a collar provided with s ringfingers, and means for preventing relative rotation of said collar withrespect to said head member.

10. A piston comprising a pair of members secured together in sleevedrelationship by a plurality of connected spring fingers, and means forpreventing rotation of either of said members relative to said fingers.

11. A piston comprising a air of members secured together in sleeverelationship by a collar provided with spring fingers,

said collar closely fitting one of said members, and certain ofoppositely disposed said fingers being received in notches in the otherof said members.

12. A iston comprising a head portion and a s 'rt portion securedtogether in sleeved relationship by resilient means, and means formaintaining the concentricity of said portions.

13. A piston comprising a head portion and a s irt portion securedtogether in sleeved relationship by resilient means, and means disposedon generally opposite sides of said piston for preventing movement ofone of said rtions laterally thereof on the other of sai portions.

14. A piston comprising a head portion and a sleeve portion, resilientmeans locking said portions against axial movement relative to eachother, and o positely disposed means engaging both sai portions forpreventing movement of said head portion laterally thereof on said skirtportion.

15. A piston as described in claim 14 in which said means comprises apair of fingers carried by one of said portions and a pair ofcooperating notches in the other of said portions; the sides of saidnotches adapted to engage the sides of said fingers being taperedwhereby to prevent said fingers from contacting against the bottoms ofsaid notches.

PHELPS M. FREER.

